As someone who does car crashes for a living, I can tell you these features are never a bad thing when used properly. They are a tool to help you, not a substitute for good driving skills (not implying you don't have them). Yes, the beeps and warnings can be annoying and they can be over sensitive. If they are, or you're in an area where the car has trouble reading road lines, etc...then maybe turn it off. The emergency braking is a wonderful thing, rear end accidents are by far the most common type. The "phantom" braking thing is amazingly overblown and hype. Has it happened? Yes. However, it's a very, very rare thing. It's far more likely to prevent an accident than cause an issue by a phantom event.
The key thing to remember is that they aren't autonomous driving. They are simply aids for the skills you should have. While the emergency braking will take over the brakes, things like the lane departure warning don't complete take over steering. You can override it if you don't agree with what it's trying to do. Some systems are better than others. No offense to Tesla owners, but I would not use their cars as a gauge.
Many here know how much of a car guy I am. I've owned probably over 100, I work with them for a living, race them for a hobby, drive 35k+ miles per year. Heck, I just bought 2 cars for my 15 year old son within the past 30 days. So I very much want to do my own driving. However, I recognize that the computers and systems can do things I never could. It's very similar to ABS. People scoffed at that idea years ago, and in fairness it did need some development. However, ABS systems can out brake even the best race car drivers in the world. Yet people still resist the "stomp and steer" braking method in snow and want to do it themselves. So technology is always slow to catch on.
